Prevention of marking off



Patented Nov. 22, 1927-.

UNITED STATES PATENT OFFICE.

CHARLES S. HOLLANDER, OF PHILADELI'HIA, PENNSYLVANIA, ASSIGNOR TO ROHM 8a HAAS COMPANY, A CORPORATION OF DELAWARE.

ranvnnrron or manxme on.

No Drawing.

which should not have any effect on the dyed yarns. This bleaching process involves two steps-first, a boiling out with caustic soda or soda ash to remove waxes or other impurities from the raw cotton yarn; and

second, a treatment with chlorine orhypochlorite solutions to remove the remaining color.

Unfortunately in the first stage mentioned, or as it is called, the kier boil, it frequently happens that someof the color is transferred from the dyed yarn to the undyed portions of the piece oods, and this occurrence has been termed marking off.

I have ,discovered that marking ofi' may be prevented by adding to the kier liquor a proper amount of a materialwhich will either have a quinone-like structure in a hot'or cold alkaline solution, or will be converted to a substance having such a structure when heated in an alkaline solution. To

the first group belong para-nitrosophenol, orthonitrosometacresol, benzoquinone, the naphthoquinones, etc.; and to the second '30. group belong such products as paranitrosodimethylaniline and its hydrochloride. Paranitrosodimethylaniline, for example, is converted into paranitrosophenol by boiling with alkali. All of these substa-nces in both groups are intended to be embraced within the term substances which show a quinonelike structure in a hot alkaline solution.

Within this phrase I do not intend to include higher substances such as those of the an- 40 thracene series, as these themselves will dye the goods with a dye that will not be removed by the subsequent bleach. Inasmuch -rite solution accordin Application filed February 25,- 1926. Serial No. 90,689.

tion of alkali in the kier, the temperature or pressure at which the goods are boiled, and also the length of time the goods are subjected to the treatment. The higher the concentration of alkali, the higher the temperature or pressure, and the longer the time is the more of these substances has to be used, but, some idea of the amount that may be used may be obtained from the following illustrative examples:

In these examples, unbleached cotton goods with colored borders, dyed with various Vat dyes, were rolled up tightly, and the roll was secured with a thread to prevent unrolling.

First ewampZe.The roll of unbleached cotton goods with vat dyed border was heated for two hours at 15 pounds pressure with twenty times its weight of water, 4% of caustic soda and 4% of orthonitrosometacresol. The goods were then unwrapped, rinsed and bleached with sodium hypochloto well-known pro-. cedure, and they shows a perfect white color without any markoif.

Second example-A roll of unbleached cotton goods with vat dyed borders was subjected to six hours boiling in an open vessel. with 3% of caustic soda and 1% of nitrosophenol and 2,000% of water. The goods were then aftertreated as beforewith the same result.

Third ezfiample.Another roll of un-, bleached, cotton goods with vat dyed pattern was boiled with 4% of caustic and 5%,% of paranitrosodimethylaniline hydrochloride,

- and enough water to submerge the goods for three hours at 15 pounds pressure. The goods were then also subjected to the same aftertreatment with the same result.

It is to be understood that these examples are given by way of illustration only, and that the temperatures, timeof treatment, and concentration, that is, the relative amounts of water and chemicals used, may be varied within wide limits without de- 95 parting from the spirit of my invention.

What I claim is: 1. In the art of bleaching fabrics which include vegetabl yarns dyed with dyes fast to alkali and chlorine bleach, the step of subjecting the goods to the action of a hot alkaline solution comprising a substance having 5 not more than two benzene nuclei which in a hot alkaline solution will show a quinonelike structure.

2. A process as defined in the foregoing claim in which the said substance comprised in the alkaline solution will show a quinone- 10 like structure in a cold alkaline solution as well as in a hot alkaline solution.

CHARLES S. HOLLANDER. 

